public class Main {
    public static void main(String[] args) {
        String s = "16_HUAWEI+Kirin+970";
        StringBuilder sb = new StringBuilder(s);
        for (int i = 0; i < sb.length(); i++) {
            if (sb.charAt(i) == '+') {
                sb.replace(i,i + 1, "%20");
            }
        }
        System.out.println(sb.toString());
        String s2 = "223344";
        s2.replace("22", "xx");
        s.replace("16", "%20");
        System.out.println(s);
        System.out.println(s2);
        System.out.println("%20");
    }
}
